Re: Grounding

In message <1155061089.408497.197070@xxxxxxxxxxxxxxxxxxxxxxxxxxx>, dated Tue, 8 Aug 2006, Richard Henry <pomerado@xxxxxxxxxxx> writes

I can't recall when I have seen a simple question (should I split groundplanes?) lead to such a fearless display of ignorance.

Now I only have to figure out which side is the ignorant one.

Neither. The reason you get two methods is that neither is fundamental. This happens in other situations, too.

The fundamental requirement is to keep the digital currents, including ground currents, out of the analogue circuits and vice versa. If you do that, ***there is no current in the ground interface between the analogue and digital circuits***. So it doesn't matter whether they are joined just at one place or along a line. If there is no current in that bit of copper, it need not be there.

Joining at one point MAY mean that it's easier to be sure you have the currents segregated. But it may not work; you can goof elsewhere, such as at power supply connections. Equally, you can get into trouble with a continuous ground-plane, because you can't see where the currents are going if they have two dimensions to play around in.
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